Dual-action decontamination system

ABSTRACT

Hydrophobic polymer particles (e.g., granules or fragments) employed as filter media, e.g., for filtering runoff water, include an antimicrobial compound on exterior surfaces and can reduce proliferation of microbial organisms as well as sorb chemical contaminants from the water. By employing this dual decontamination action, filter systems employing such particles can improve the quality of runoff water (or other contaminated water streams) and reduce the risk presented by potentially harmful organisms.

BACKGROUND OF THE INVENTION

[0001] Typical water runoff contains a surprisingly large amount of oiland other contaminants. The resulting contamination of natural receivingwater incurs enormous annual costs, both financial and environmental.For example, a government study in one published article showed thatstorm water sampled from street sites contained an “event meanconcentration” of 2.2 mg. of oil per liter of runoff water. Shepp,“Petroleum Hydrocarbon Concentrations Observed in Runoff from Discrete,Urbanized Automotive-Intensive Land Uses,” Watershed '96. If one meterof rain per year falls on a street 10 meters wide, then at that observedmean rate, the annual runoff from each kilometer of street will containabout 275 liters of hydrocarbons.

[0002] Various systems have been developed to remove hydrocarbons andother chemical contaminants from runoff water. For example, U.S. Pat.No. 6,080,307, and commonly owned with the present application,discloses a system for recovering trash and oil from water passing intostorm drains or the like.

[0003] Unfortunately, a report of the National Resources Defense Council(“Testing the Waters 2001,” available from www.nrdc.org) makes it clearthat such conventional systems for chemical decontamination and debrisremoval are inadequate for effective purification of runoff water.Eighty-five percent of beach closings and health advisories occurring in2000 were the result of high bacteria levels, according to the report,and “polluted runoff and storm water caused or contributed to more than4,102 closings or advisories.” Clearly there remains a need for furtherimprovements in the purification of runoff water to alleviate continuedconcerns about public health.

SUMMARY OF THE INVENTION

[0004] In accordance with aspects of the present invention, includingvarious advantageous methods, hydrophobic polymer granules or fragmentsemployed as filter media, e.g., for filtering runoff water, include anantimicrobial compound on their surfaces. Advantageously, such polymergranules or fragments are able to reduce proliferation of microbialorganisms in the water in addition to sorbing chemical contaminants fromthe water. (As used herein, “reduce proliferation” includes reducingcounts or concentrations of live or otherwise active microorganisms,preventing microorganisms from reproducing or otherwise proliferating,or both.) By employing this dual decontamination action, filter systemsemploying such particles can further improve the quality of runoff water(or other water streams) and reduce the risk presented by potentiallyharmful organisms in the water.

[0005] In a particularly advantageous method of the invention forpreparing filtering and decontamination media, polymer granules havinghigh sorbency for one or more predetermined contaminant liquids, such asoil or other hydrocarbons, are irrigated with a solution that contains areactive antimicrobial compound. (As used herein, the term “irrigate”means applying solution to a polymer material by any suitable technique,including spraying, static immersion, centrifugal innundation, orconjoined fluid flow of particles and solution.) The polymer granulesare phobic to water (i.e., hydrophobic) and to the liquid of thesolution (which may itself be water) and thus do not sorb anysignificant quantities of the solution even during irrigation. Becausethe antimicrobial compound in the solution is reactive, it becomesgrafted to the polymer surfaces of the granules without the solutionbeing substantially sorbed (i.e., absorbed or adsorbed) by the granules.The resultant polymer granules are capable, upon immersion incontaminated water, of both sorbing contaminant liquids and reducingbiological contamination in the water, a clearly beneficial property.

[0006] The method can also include drying (at least substantially) thesolution-irrigated polymer granules and then extruding the polymergranules into fragments of filter media. Alternatively, the method caninclude forming unirrigated granules into fragments of filter media,such as using an extrusion process, then irrigating the formedfragments. Although many of the embodiments disclosed herein aredescribed with reference to irrigated granules later formed intofragments, the inventor also contemplates alternatives using granulesformed into fragments and then irrigated. The method can further includesupporting the fragments about an open recess within a filter module.When the contaminant liquids include hydrocarbons, such a filter moduleis capable of both removing oil from water passing into the open recessand reducing proliferation of microbial organisms in the water. Thus, anadvantageous result of the method is a further improvement in thepurification of runoff water over that which is conventionallyavailable.

[0007] A fragment of filter media according to one aspect of theinvention is comprised of: a matrix of compliant, hydrophobic, olefinicpolymer; an oil-sorbent, hydrophobic copolymer in the matrix; and anantimicrobial compound. The antimicrobial compound can be grafted, inone useful embodiment, e.g., by the advantageous method mentioned above,to a portion of the polymer of the matrix and to a portion of theoil-sorbent, hydrophobic copolymer in the matrix. Altermatively, theantimicrobial compound can be granted to the copolymer alone (or,although less preferred, to the granules of the matrix alone).Consequently, the fragment is advantageously capable of both sorbing oilfrom surrounding water and reducing proliferation of microbial organismsin the water. (As used herein, the term “particles” refers to eithergranules or fragments, including granules in loose form as well asgranules formed into fragments, and including fragments alone or linkedto adjacent fragments to form a coherent polymer body of macroscopicdimensions.)

[0008] A filter system according to another aspect of the inventionincludes a multitude of irregular, macroscopic fragments of the typediscussed above and a filter module that supports the fragments about anopen recess. Such a filter system is highly desirable in that it canperform the dual-action decontamination of both sorbing oil, grease,etc. from water passing into the open recess and reducing proliferationof microbial organisms in the water or in residues left in (or between)the filtering fragments or the filter module.

[0009] Also highly desirable is a method of the invention for improvingchemical and biological purity of water entering a storm drain. Themethod includes sorbing one or more targeted contaminants from the waterby directing flow of the water through interstices of a multitude ofirregular, macroscopic fragments that are sorbents of the contaminants,e.g., fragments of the type discussed above. In the method, thefragments include an antimicrobial compound on their surfaces, e.g., areactive compound grafted to surfaces of polymer fragments.Proliferation of microbial organisms in water passing over thosesurfaces is advantageously reduced even as chemical contaminants aresorbed from the water.

[0010] These and other compositions, systems, and methods of theinvention can employ particular materials according to various aspectsof the invention for particularly favorable results. First, theantimicrobial compound can be an organosilane compound not susceptibleto self-condensation in water, which avoids the use of more hazardoussolutions. Second, the contaminant-sorbent, hydrophobic copolymer can bestyrene-butadiene-styrene (SBS) or hydrogenated styrenic block copolymer(“SEBS”), both of which are highly oil-sorbent, non-toxic, and remaincoherent after becoming oil-saturated. The compliant, hydrophobicpolymer can be ethylene propylene diene monomer (EPDM) or ethylenepropylene monomer (EPM), both of which permit formation of a polymermatrix that supports the oil-sorbent, hydrophobic copolymer while alsoabsorbing a certain quantity of oil.

[0011] The above summary does not include an exhaustive list of allaspects of the present invention. Indeed, the inventor contemplates thatthe invention includes all systems and methods that can be practicedfrom all suitable combinations of the various aspects summarized above,as well as those disclosed in the detailed description below andparticularly pointed out in the claims filed with the application. Suchcombinations have particular advantages not specifically recited in theabove summary.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Various embodiments of the present invention are described belowwith reference to the drawings, wherein like designations denote likeelements.

[0013]FIG. 1 is a detail view of a section through a copolymer fragmentthat includes an antimicrobial compound on its surface according tovarious aspects of the invention.

[0014]FIG. 2 is an outline of the copolymer fragment of FIG. 1.

[0015]FIG. 3 is a cutaway perspective view of a filter system employingfilter media including copolymer fragments of the type of FIG. 1.

[0016]FIG. 4 is a process flow diagram of a method for fabricating thecopolymer fragment of FIG. 1.

[0017]FIG. 5 is a cutaway perspective view of a filter cartridgeemploying filter particles that have been irrigated with anantimicrobial solution after agglomeration of the particles into a massof filter media according to various aspects of the invention.

DESCRIPTION OF PREFERRED EXEMPLARY EMBODIMENTS

[0018] In various methods and systems according to aspects of thepresent invention, a multitude of hydrophobic polymer granules orfragments employed in filter media include (or are made to include) anantimicrobial compound on their surfaces. Such a configuration providesa significant benefit in allowing the polymer material to reduceproliferation of microbial organisms in the water or on the materialwhile retaining their ability to sorb chemical contaminants from thewater. By employing this dual decontamination action, filter systemsemploying such granules or fragments can further improve the quality ofrunoff water (or other water streams) and reduce the risk presented bypotentially harmful organisms in the water or in filters.

[0019] In an exemplary method that may be better understood withreference to FIG. 3, for example, runoff water (not shown) enters acurb-inlet 306 of a storm drain and passes into exemplary filter system300, which includes a hopper 310. After entering hopper 310, the waterpasses through a screen of a basket 320, which traps trash items, andinto a quantity of filter media including polymer fragments 130.Fragments 130 perform the dual action of sorbing contaminants andreducing the proliferation of microbial organisms in the water as itpasses through interstices of the fragments. Consequently, overallpurity of water passing out of hopper 310 (through perforated steel orplastic bottom 340) is improved both chemically and biologically.

[0020] Additional disclosure of system 300 is found in commonly ownedU.S. Pat. No. 6,106,707 entitled “Curb-Inlet Storm Drain Systems forFiltering Trash and Hydrocarbons,” to Morris and Stelpstra, referred toherein as the '707 Patent. As with all patents referenced herein, the'707 Patent is incorporated herein by reference along with any documentsincorporated by reference therein.

[0021]FIGS. 1 and 2 illustrate an example of a suitable copolymerfragment 130, for use inside compartment 310 of system 300. Fragment 130includes an EPDM or EPM matrix 390 that forms a durable but permeablestructure for SBS granules 380 and provides mechanical integrity tofragment 130. Surfaces of the SBS granules (e.g., surface 110 orsurfaces in interstices 370) and preferably also the EPDM or EPM matrixinclude an antimicrobial compound for dual-action decontamination.

[0022] The '707 Patent discloses a preferred type of polymer forgranules and fragments according to various aspects of the invention.When oil-water runoff comes into contact with the fragments, thecopolymer material will absorb and entrap the oil. Because the copolymermaterial is hydrophobic, however, it will not become water-logged, andwater will pass through the filter module. After the copolymer materialhas absorbed oil, subsequent runoff flowing past the material will notwash away the oil. Indeed, it has been found that the materialsdescribed herein can remain in contact with water continuously for atleast several months, and perhaps indefinitely, without releasing theoil or allowing it to emulsify.

[0023] The principal ingredient of fragment 130 is a copolymericmaterial that is known to sorb oil but not water. As oil entersfragments 130, they expand somewhat. Thus, it is preferred to avoidfilling compartment 310 (FIG. 3) completely with fragments 130, toprevent fragments 130 from pushing upwards into basket 320 as theyexpand with oil absorption.

[0024] Particularly suitable types of copolymers fall within the classof thermoplastic elastomers, such as styrene-butadiene-styrene (“SBS”),and hydrogenated styrenic block copolymer (“SEBS”), both of which arestyrenic block copolymers. Styrenic block copolymers were developed forapplications that require impact resistance, and that is still theirprimary use. SBS and SEBS are highly sorbent, non-toxic, and remaincoherent after becoming oil-saturated. An alternative styrenic blockcopolymer, which may be employed in granules and fragments according tovarious aspects of the invention if the benefits of SBS and SEBS are notrequired, is styrene-isoprene-styrene (“SIS”).

[0025] In a preferred filter media fabrication method 400, discussedbelow with reference to FIG. 4, SBS material formed into granules ismixed with granulated binder material. In that embodiment, granularporous SBS with about 30% styrene has been found suitable, when siftedto retain pieces in the range of sizes between 4 and 24 mesh.Preferably, the SBS product is manufactured without talc, contrary tothe standard manufacturing process, to enhance inter-granular linking orbonding in the formed body.

[0026] The binder material is a compliant or flexible, hydrophobic,olefinic polymer material in a granular form and preferably having amelting point lower than that of the oil-absorbent copolymer.Polyolefinic elastomers, such as ethylene propylene monomer (“EPM”) orethylene propylene diene monomer (“EPDM”) have been found suitable. Thebinder largely prevents fragments 130 from crumbling while being handledin dry form yet also absorbs a certain quantity of oil. In a preferredembodiment, EPDM granules sifted to retain pieces between 12 and 24 meshwere found suitable. Pieces in the range of 6-24 mesh can also besuitably employed.

[0027] About 70-90% by weight of the material of fragments 130 consistsof SBS, and the remainder consists of EPDM binder in a preferredembodiment. As explained below, SBS and EPDM granules are linked andformed into fragments 130 in a way that results in SBS granules in anEPDM matrix.

[0028] In addition to having antimicrobial compound on their surfacesaccording to various aspects of the invention, polymer fragmentsaccording to various aspects of the invention are preferably fabricatedwith two main design goals in mind. First, the flow of desired liquid(e.g., water to be decontaminated) should not be unduly restricted.Restricted liquid flow limits the rate at which the liquid can bepurified and decontaminated. Second, the liquid should be prevented, tothe extent practical, from collecting into channels. When liquidcollects into channels within a mass of filter media, it tends to comeinto contact with only the limited amount of treated filter media thatsurrounds the channels. Fragments 130 are irregularly shaped and not inpowder form, which addresses the first concern by preventing them frombeing too compactly packed inside compartment 310 of FIG. 3, becausethat may restrict the flow of water. The random shapes of fragment 130address the second concern by moving liquid laterally in compartment310, thereby further reducing the tendency of the liquid to collect intochannels.

[0029] To permit faster oil absorption and less gel blocking (aphenomenon in which a layer of absorbed oil at the exterior blocksaccess to inner portions of fragments 130), without increasing thedistance from surface to center, it is desirable to avoid smoothexterior “skins” on outer surfaces of fragments 130. The preferredprocess of formation discussed below promotes this goal.

[0030] Also to reduce gel blocking, fragments 130 preferably havenumerous fissures 370 extending into them from exterior surfaces andpassing between the grains of SBS, as illustrated in FIG. 1. Suchfissures increase the effective surface area of fragments 130 whilestill maintaining each as a coherent whole, permitting easy handling.The preferred formation process discussed below promotes this goal.

[0031] In one example, fragments 130 consisted primarily of irregularlyshaped objects with various dimensions about a centimeter or two across.Those exemplary fragments 130 were formed of 78% SBS and 22% EPDM andhad a bulk density of about 0.4-0.6 g/cc and mostly weighed about 2 to 3grams each. Some of the fragments had broken into smaller pieces, someof which weighed as little as 0.3 to 1 grams. A few fragments consistedof pairs of normally sized fragments that had linked together, forminglarger fragments about 5 to 6 grams each.

[0032] Fragments 130 have controlled bulk density, also to reduce gelblocking. With the preferred materials discussed above, bulk densitygreater than 0.75 g/cc tend to prevent the oil from entering thefragments, while bulk density smaller than 0.3-0.35 g/cc cause thefragments to fragment more easily, either when dry or after absorbingoil. For example, copolymer fragments 130 with a bulk density in thepreferred range have enough inter-granular voids to permit oil topenetrate substantially throughout the thickness of the larger fragments130, thereby avoiding gel blocking, while leaving them mostly intact.Fragments of such material can absorb up to five times their weight inoil.

[0033] In variations of method 400, SEBS is substituted for SBS, EPM issubstituted for EPDM, or both. In another variation, fragments 130 areirrigated with a solution containing an antimicrobial compound afteraggregation of the fragments in a container or agglomeration of thefragments into a coherent block of filter media. In yet anothervariation, SBS granules 410 are irrigated with a solution containing anantimicrobial compound separately from EPDM granules, which are eitherirrigated or not.

[0034] Fragments 130 of exemplary filter system 300 can have anysuitable type of antimicrobial compound on their surfaces, applied byany suitable technique. A particularly advantageous method of theinvention for fabricating media having contaminant-sorbent andantimicrobial properties includes irrigating a multitude ofcontaminant-sorbent polymer granules with a solution containing anantimicrobial compound, followed by extrusion of the granules intofragments. In the method, the antimicrobial compound and the polymer ofthe granules are reactive together, and the polymer is substantiallyphobic to water and to the solution. An antimicrobial compound andpolymer are reactive together whenever the compound, in solution, can beexpected to graft to the polymer. A compound grafts to a polymerwhenever it forms covalent bonds with it.

[0035] The use of a polymer that is hydrophobic and also phobic to thesolution (which itself may be water), is particularly advantageousbecause granules and fragments of such a polymer will not sorbsignificant amounts of water (during filtration) or solution (duringgrafting of the antimicrobial compound from the solution).

[0036] Method 400 of FIG. 4 begins with initial materials of SBSgranules 410, EPDM granules 420, and an antimicrobial solution 430. Anorganosilane antimicrobial compound not susceptible to self-condensationin water is particularly desirable for use in solution 430 for a numberof reasons including the fact that the solution can be or include water.

[0037] One suitable compound is of the type described in U.S. Pat. No.5,954,869 to Elfersy et al. (referred to herein as “the '869 Patent”),hereby incorporated herein by reference, particularly the portion fromColumn 5, line 20 through Column 22, line 8. The terminology used in the'869 patent is employed only for the purpose of describing particularembodiments. Accordingly, nothing in the description of exemplaryantimicrobial agents in the '869 Patent or its file history is intendedas limiting. As used herein and in the '869 Patent, the singular forms“a,” “an” and “the” include plural referents unless the context clearlydictates otherwise. A suitable commercial product of this type isidentified as “AM-500” and marketed by Bioshield Technologies, Inc. ofNorcross, Ga.

[0038] The term “effective amount” of a compound, product, orcomposition means an amount sufficient to provide the desired result. Aspointed out in the '869 Patent, the exact amount required will vary fromsubstrate to substrate, depending on the particular compound, product,or composition used, its mode of administration, and the like. Thus, itis not always possible to specify an exact “effective amount.” However,an appropriate effective amount may be determined by one of ordinaryskill in the art informed by the instant disclosure using only routineexperimentation.

[0039] As used herein and in the referenced '869 Patent, the term“antimicrobial” has a general meaning, referring to the property of thedescribed compound, product, composition, or article to reduce theproliferation of microbial organisms, i.e., to prevent or reduce thegrowth, spread, formation or other livelihood of the organisms.Microbial organisms include bacterial pathogens, viruses, protozoa,molds, or other organisms likely to cause spoilage or infection, and ofcourse can also include organisms whose proliferation is not necessarilya problem, e.g., “friendly” bacteria.

[0040] Method 400 begins with act 440, representing mixing the SBS andEPDM granules together at the particle level. Mixing need not beentirely thorough to be effective. Mixing can simply consist of dumpinggranules 410 and 420 into a common volume of solution, in which case thenext act 450 of method 400 is performed together with mixing act 440.

[0041] Act 450 represents irrigating the mixture to graft antimicrobialcompound in solution 430 to polymer of granules 410 and 420. Asmentioned above, irrigation of granules with solution can be performedin a number of different ways. Accordingly, process 450 has manypossible variations, including immersing granules 410 and 420 insolution 430, spraying solution 430 onto granules 410 and 420, applyinga stream of solution 430 to granules 410 and 420 inside an operatingcentrifuge, etc. Irrigation continues until an amount of graftingdesirable for a particular implementation has taken place. In oneembodiment of act 450, granules are immersed in an “AM-500”antimicrobial solution (2%-10% concentration of antimicrobial agent, bymass) for five minutes at room temperature. Preferably, the resultantantimicrobial-grafted granules contain at least about 0.5% antimicrobialagent, by mass.

[0042] Many variations of method 400 can be suitably employed. In onevariation, for example, acts 440 and 450 are performed simultaneously,e.g., by dumping granules of each type into a static or stirred volumeof solution where they are mixed and irrigated. In another variation,processes 440 and 450 are performed in a sequence opposite that depictedin FIG. 4. In such a variation, granules are irrigated (and perhaps alsodried) in separate subprocesses before they are mixed together. In othervariations where the benefits of irrigating both SBS and EPDM are notrequired, granules of just one type of polymer are irrigated. Forexample, just SBS can be irrigated if the EPDM matrix of the eventualpolymer fragment does not need to have the benefit of antimicrobialproperties.

[0043] The product of act 450 is a mixture of granules 410 and 420 withantimicrobial compound grafted to polymer of the granules and with someresidual solution in the mixture. Act 460 represents drying the liquidfrom the mixture. In the example of method 400, act 470 representsextrusion of the dried granules into fragments by process 470. Invariations where the benefits of drying act 460 or any subsequentprocessing are not required, they can be suitably omitted. In suchvariations, the end product is considered to be the product of act 450.

[0044] Drying act 460 can be performed by any suitable technique,including simply exposing the mixture of granules to a static air massat ambient temperature. More efficient drying techniques, such asforced-air or heated drying can also be employed. The extent of dryingdepends on the need to a particular implementation. Overnight staticdrying is a suitable option for methods involving extrusion of thegranules into fragments, e.g., by act 470. Preferably, act 460 dries themixture of granules until the amount of solution liquid remaining in themixture is less than 0.3-0.5%, by weight, as measured using a weightcomparison before and after heat treatment analysis at 140°.

[0045] Act 470 represents extrusion of the mixed, dried granules graftedwith antimicrobial compound that result from acts 440-460 into fragmentsof filter media such as fragments 130 of FIGS. 1-3. In an exemplaryimplementation of extrusion process 470, the SBS and EPDM granules areplaced in the hopper of an extruder of conventional design (e.g., atwo-inch Bonnot lab extruder with a hot-water external barrel heatexchanger, run at 40 RPM), which in one embodiment of the extrusionprocess maintains the temperature of the granular material near about115°-135° F., far below normal extrusion temperatures for plasticproducts. The heat exchanger should not permit the temperature of thegranular material to exceed 160° F. As discussed below, a particularlyadvantageous method of forming filter media permits SBS fragments tobecome agglomerated while still warm enough to establish molecularbonds.

[0046] In the barrel of the extruder, the EPDM quickly becomes softened,as a result of heat caused by shearing forces that result frommechanical agitation by the screw. To maintain the temperature of thegranular material near the desired temperature, the heat exchangertypically acts as a cooling device to conduct some of this heat awayfrom the material. At the beginning of the process and any otherappropriate times, the heat exchanger can apply heat to the material toraise it to the desired temperature.

[0047] The extruder's screw mixes the softened EPDM and the SBS, forminga matrix of EPDM surrounding and interlinked to SBS granules. Becausethe SBS does not melt, some air spaces (i.e., bubbles) remain in themixture. The softening process occurs quite rapidly in the extruder,permitting very short dwell times (such as less than one minute), whichpermits rapid manufacturing.

[0048] The composite material is pressed through a circular die with acentral rod or mandrel (not shown), at a unit flow rate of about 6g/sec. in one embodiment using a cross section of particular size. Ifleft undisturbed at this flow rate, the material would form acylindrical body with an axial hole. However, radial arms at the end ofthe die, or a similarly configured cutter just outside the nozzle (notshown), section the cylindrical bodies into segments, perhaps foursections. An automatic knife (not shown) fires every two seconds or so,cutting off lengths of the sections.

[0049] Another way of producing such fragments is to use a smaller die,with a hole approximately one centimeter across, to produce thefragments directly rather than by cutting them radially from acylindrical form.

[0050] Upon passing through the die, the SBS granules, which havecompressed somewhat from being forced through the die, re-expand,“fluffing” the extruded material while it slowly cools. Air remaining inthe mixture further assists the expansion. After the extruded materialis cut into suitable lengths, it slowly cools outside the extruder, andthe granules continue to expand for a time, causing additional fluffing.

[0051] The EPDM matrix 190 (see FIG. 1) forms a durable but permeablestructure for the SBS granules 180 and provides mechanical integrity toresulting fragments 130. Thus, fragments 130 formed in accordance withthe preferred method resist breaking or cracking absent extreme elasticdeformation, despite the presence of fissures 370. Also, fragments ofsuch bodies do not detach easily in the form of flakes, crumbles, ordust.

[0052] The fluffing effect (conventionally undesired in extrusionprocesses) is actually beneficial in the inventive process because itforms inter-granular fissures 370 in the EPDM matrix, throughout thestructure. However, the fissuring is not so great as to cause loss ofstructural integrity. As noted above, fissures are preferred tofacilitate rapid passage of oil into fragments 130 and to reduce theincidence of gel blocking, permitting continued absorption.

[0053] Slight irregularities in the flow rate, the fluffing effect, andthe way in which the knife cuts the material can cause fragments ofdifferent sizes to form. For example, a larger-than-normal fragment canform when two adjacent sections link together. A smaller-than-normalfragment can form when a section breaks apart if fissuring caused byfluffing happens to occur along a fracture line. The resulting fragments130 are similar in size and general appearance to popcorn.

[0054] In another advantageous method of the invention, irrigation ofgranular precursors to polymer fragments is replaced by irrigation ofthe polymer fragments themselves with a solution containing anantimicrobial compound. In another advantageous method of the invention,a mass of polymer filter media (e.g., comprised of agglomerated orloosely connected polymer fragments) is suitably irrigated with asolution containing an antibacterial compound. For example, a filtermodule according to various aspects of the invention can “filter” arecirculating stream of such solution for sufficient time to ensuregrafting of antimicrobial compound to significantly all polymer surfacesthat can be expected to contact liquid to be purified during the filtermodule's actual use. Alternatively, such a filter module can be immersedin a static volume of antimicrobial solution for a suitable graftingtime.

[0055] As mentioned above, a particularly advantageous method of formingfilter media forms a coherent block of filter media from fragments ofmedia that become agglomerated while warm enough to establish molecularbonds between fragments. In the method, the fragments are fed directlyfrom a heat-generating process (e.g., extrusion) into a form. Thefragments are allowed to cool after suitably filling the form to form acoherent block of media within the form. The form can then be removed(e.g., by shearing) or left in place as structure for containing theblock of media. In a variation of filter system 300 employing such ablock of media, for example, hopper 310 can be replaced with the block.In such a variation, the block can be suspended from a bracket byflexible support structure and a tray that is dimensioned to support theblock on it. Pertinent disclosure is found in the brochure “ULTRA-URBANfilter with OARS Onboard,” presently available atwww.abtechindustries.com and the web pagewww.abtechindustries.com/Ultra_UrbanFilter.htm, both of which documentsare incorporated herein by reference.

[0056] An advantageous variation of a filter module according to variousaspects of the invention houses filter media within a cartridge. Duringoperation, such a filter module directs water flow through the cartridgeand through the filter media housed in it. An exemplary filter module500, which may be better understood with reference to FIG. 5, includes acartridge 540 having apertures 520 and 530, shown in this embodiment asbeing at opposite ends. Cartridge 540 is packed with polymer filtermedia 510 (or alternatively contains a quantity of such media withoutbeing packed) that includes an antimicrobial compound grafted to it.Filter media 510 can have the antimicrobial compound grafted to it byone or more of the following: (1) irrigating polymer granules with anantimicrobial solution of the type discussed above and forming them intofragments; (2) irrigating polymer fragments formed from polymer granules(or other polymer precursor structures); or (3) irrigating filter mediaformed from polymer fragments (or other polymer precursor structures),for example by subjecting bound fragments (whose particulate structuremay be lost after being agglomerated) of filter module 500 torecirculating flow of antimicrobial solution via apertures 520 and 530.

[0057] In a further variation, flow of water (or other liquid to bedecontaminated) is directed into a central aperture of a cylindricalaggregation or agglomeration of polymer particles having antimicrobialcompound grafted to them. The water is forced radially outward throughthe filter media comprised of the particles to exit the filter modulethrough a porous outer wall of the filter media cylinder. The preferredradius of the cylinder is between about 4 and 5 inches.

[0058] The detailed description of preferred exemplary embodiments abovementions the detailed description portions of certain patents andpublicly accessible documents (including U.S. Pat. Nos. 6,106,707 and5,954,869), all of which are hereby incorporated herein by reference.The detailed description portions of all materials incorporated byreference into these listed patents or applications, including U.S. Pat.Nos. 5,411,585; 5,064,613; 5,145,592; and 4,390,712, and the publicationentitled “A Guide to DC Silane Coupling Agent” (Dow Corning, 1990), arealso specifically incorporated herein by reference.

PUBLIC NOTICE REGARDING THE SCOPE OF THE INVENTION AND CLAIMS

[0059] The inventor considers various elements of the aspects andmethods recited in the claims filed with the application asadvantageous, perhaps even critical to certain implementations of hisinvention. However, the inventor regards no particular element as being“essential,” except as set forth expressly in any particular claim.

[0060] While the invention has been described in terms of preferredembodiments and generally associated methods, the inventor contemplatesthat alterations and permutations of the preferred embodiments andmethods will become apparent to those skilled in the art upon a readingof the specification and a study of the drawings. For example,particular variations can employ of an antimicrobial compound other thanan organosilane compound not susceptible to self-condensation in water.In other variations, polymer granules or fragments according to variousaspects of the invention can be employed in pipes, industrial filtrationsystems, filtration cartridges, and any other types of systems where thedual-action decontamination performed by such granules and fragments isdesired.

[0061] Accordingly, neither the above description of preferred exemplaryembodiments nor the abstract defines or constrains the invention.Rather, the issued claims variously define the invention. Each variationof the invention is limited only by the recited limitations of itsrespective claim, and equivalents thereof, without limitation by otherterms not present in the claim. For example, method claims that do notrecite acts regarding drying and extrusion read on methods that include,and exclude, such acts.

[0062] In addition, aspects of the invention are particularly pointedout in the claims using terminology that the inventor regards as havingits broadest reasonable interpretation; the more specificinterpretations of 35 U.S.C. § 112(6) are only intended in thoseinstances where the terms “means” or “steps” are actually recited. Thewords “comprising,” “including,” and “having” are intended as open-endedterminology, with the same meaning as if the phrase “at least” wereappended after each instance thereof.

What is claimed is:
 1. A method for fabricating media havingcontaminant-sorbent and antimicrobial properties, the method comprising:(a) irrigating a multitude of contaminant-sorbent polymer particles witha solution containing an antimicrobial compound; wherein (b) theantimicrobial compound and the polymer of the particles are reactivetogether; and (c) the polymer is substantially phobic to water and tothe solution; whereby the antimicrobial compound grafts onto the polymerparticles and, upon contact with water, the polymer particles sorbcontaminants from the water and reduce proliferation of microbialorganisms.
 2. The method of claim 1 wherein irrigating particlescomprises irrigating a multitude of loose granules or fragment with thesolution, wherein substantially all surfaces of each individual particleis exposed to the solution.
 3. The method of claim 1 wherein irrigatingparticles comprises irrigating a multitude of polymer particles that arehydrocarbon-sorbent.
 4. The method of claim 3 further comprising: (a)substantially drying the solution from polymer particles that aregranules; and (b) extruding the polymer particles into fragments offilter media.
 5. The method of claim 4 further comprising supporting thefragments about an open recess within a filter module, whereby thefilter module is capable of both removing oil from water passing intothe open recess and reducing proliferation of microbial organisms. 6.The method of claim 1 wherein providing the solution comprisesproviding, dissolved in water, a quantity of an organosilane compoundnot susceptible to self-condensation in water.
 7. The method of claim 6further comprising dissolving the organosilane compound in the water toprepare the solution.
 8. The method of claim 1 wherein irrigating thepolymer particles with the solution comprises immersing the particles ina static volume of the solution for a predetermined period of time. 9.The method of claim 1 wherein: (a) irrigating the polymer particlescomprises irrigating particles substantially consisting of a mixture of:(1) particles of styrene-butadiene-styrene or hydrogenated styrenicblock copolymer; and (2) particles of ethylene propylene monomer orethylene propylene diene monomer; (b) the particles of ethylenepropylene monomer or ethylene propylene diene monomer comprise about10-30% of the mixture, by weight; and (c) the particles ofstyrene-butadiene-styrene or hydrogenated styrenic block copolymer arecomprised of about 25-45% styrene and are in the range of about 4-20mesh.
 10. A fragment of filter media comprising: (a) an oil-sorbent,hydrophobic copolymer in a matrix of compliant, hydrophobic, olefinicpolymer; and (b) an antimicrobial compound grafted to the copolymer andpolymer; whereby the fragment is capable of both sorbing oil fromsurrounding water and reducing proliferation of microbial organisms. 11.The fragment of claim 10 wherein: (a) the antimicrobial compound is anorganosilane compound not susceptible to self-condensation in water; (b)the compliant, hydrophobic polymer is ethylene propylene monomer orethylene propylene diene monomer; and (c) the oil-sorbent, hydrophobiccopolymer is styrene-butadiene-styrene or hydrogenated styrenic blockcopolymer.
 12. A filter system comprising: (a) a multitude of irregular,macroscopic fragments comprised of an oil-sorbent, hydrophobic copolymerin a matrix of compliant, hydrophobic polymer; (b) an antimicrobialcompound grafted to the fragments; and (c) a filter module supportingthe fragments adjacent to an aperture; whereby the filter system iscapable of both sorbing oil from water passing into contact with thefragments via the aperture and reducing proliferation of microbialorganisms.
 13. The filter system of claim 12 wherein the antimicrobialcompound is an organosilane compound not susceptible toself-condensation in water.
 14. The filter system of claim 12 wherein:(a) the compliant, hydrophobic polymer is ethylene propylene monomer orethylene propylene diene monomer; and (b) the oil-sorbent, hydrophobiccopolymer is styrene-butadiene-styrene or hydrogenated styrenic blockcopolymer.
 15. A method for improving chemical and biological purity ofa water stream containing contaminants, the method comprising directingflow of the water stream through interstices of a multitude ofirregular, macroscopic fragments that: (a) are hydrophobic but sorbentof the contaminants; and (b) have antimicrobial compound on theirsurfaces; whereby one or more targeted contaminants are sorbed from thewater and proliferation of microbial organisms is reduced.
 16. Themethod of claim 15 wherein, prior to directing flow of the water stream,the water stream contains hydrocarbons and wherein the fragments aresorbent of hydrocarbons.
 17. The method of claim 16 wherein directingflow comprises directing flow of the water through fragments furthercomprised of: (a) a matrix of compliant, hydrophobic polymer; and (b) anoil-sorbent, hydrophobic copolymer in the matrix.
 18. The method ofclaim 17 wherein directing flow comprises directing flow of the waterthrough fragments further comprised of an antimicrobial compound graftedto: (a) a portion of the polymer of the matrix; and (b) a portion of theoil-sorbent, hydrophobic copolymer in the matrix.
 19. The method ofclaim 18 wherein directing flow comprises directing flow of the waterthrough fragments wherein the antimicrobial compound grafted theretocomprises an organosilane compound not susceptible to self-condensationin water.
 20. The method of claim 18 wherein directing flow comprisesdirecting flow of the water through fragments wherein: (a) thecompliant, hydrophobic polymer consists of ethylene propylene monomer orethylene propylene diene monomer; and (c) the oil-sorbent, hydrophobiccopolymer consists of styrene-butadiene-styrene or hydrogenated styrenicblock copolymer.